We present LCT SG, an LSC (Live Sequence Chart) consistency testing system, which takes LSCs and symbolic grammars as inputs and performs an automated LSC simulation for consistency testing. A symbolic context-free grammar is used to systematically enumerate continuous inputs for LSCs, where symbolic terminals and domains are introduced to hide the complexity of different inputs which have common syntactic structures as well as similar expected system behaviors. Our symbolic grammars allow a symbolic terminal to be passed as a parameter of a production rule, thus extending context-free grammars with context-sensitivity on symbolic terminals. Constraints on symbolic terminals may be collected and processed dynamically along the simulation to properly decompose their symbolic domains for branched testing. The LCT SG system further provides either a state transition graph or a failure trace to justify the consistency testing results. The justification result may be used to evolve the symbolic grammar for refined test generation.